Just started getting serious about my work an need advices

So a few questions started to pop-up in the last month as I'm trying to be more out there.

1. I distribute through soundcloud and was wondering how to get ownership/merge my youtube account and the one youtube created for me. (I don't really mind the other plateforms since I didn't have an account prior.)

2. I'm aware I need a static cover for the tracks but I also want to start adding videos and visualizers. Soundcloud's distribution doesn't allow it so how do I work around that?

3. I noticed that my masters are often way, like WAYYYY less loud than other tracks out there even tho I'm near peaking and reach 7-8db LUFs short term and an average of 10-11db LUFs integrated. Why is that? What am I doing wrong? Should I ignore true peak and gain 2-3 LUFs risking clipping?

4. Feel free to add other things I might miss out on, I'm really clueless other than the process from production to mastering, thats where I'm starting to get confused.

TL:DR, give me tips about releasing my tracks.